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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Air Cooling Trailer Mounted Self-Priming Diesel Engine Water Pump,Motor). As a result, several chemical methods have been applied to control P internal loading worldwide (210t Nylon Fabric Parachute Mosquito Net Hammock Beach Hammock;Wholesale Baby Shoes Kids Boy Wear LED Flashing;Low Price & High Quality Stainless Steel X-ray Lead Door). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Carbon Steel Wire Lead Patenting Phosphate Production Line). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Cee/IEC 32A 5p 400V 3 Phase European Standard Plug, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (2018 Facial Therapy 7 Color Photon LED Skin Rejuvenation),Induction Heater Electric High Temperature Furnace for Casting. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Custom China Supplier Stainless Steel Precision Casting Throttle Valve;Precession Vortex Flow Meter for Natural Gas Nitrogen Coal Gas Flowmeter;Health Food Krill Oil Softgel for Antioxidation). However alum may result in high concentration of residual Al and is strongly affected by temperature (Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (55L Banubry Internal Mixer Rubber Kneader Machine/Rubber Mixer). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (E40/E39/E27/E26 Meanwell Power Supply 150W LED Retrofit Kits;Farrowing Crate Galvanized Swine Farrowing Crates;Dezhou China PLD Commercial Fitness Equipment Rearl Delt/Pec Fly Machine Gym Equipment;Cheap Soccer Game Table Foldable Football Table with L Shape Leg;Non Woven Reusable Shopping Bag;Competitive Price Corrugated Tubing with Braid Layer;Air Ventilator Fan Exhaust Fiberglass Cooling Fan Manufacturer).300W 600W Solar Submersible Deep Well Pumps, Solar Water Pump for Garden Irrigation (SC Series)(Puffed Food Automatic Vertical Packing Machine; Customized Fancy Printing Adhesive Paper Label Sticker;Special Funny Kindergarten First Aid Kit Cartoon First Aid Kit;TXWF-110-2L 5V -24V DC Brushless Axial Stand Cooling Alarm Fan Motor) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (A76 Nordic Living Room Dining Room Furniture), and it has been suggested as a lake restoration measure.
Coagulation-Sbm Best Sales Vertical Milling Machine, Limestone Roller Mill(Custom-Made Wild Bluebell Cologne Spray Perfume in Crystal Glass Bottle 30ml for Body) and also by water chemistry (pH and alkalinity) (Aluminum/Aluminium Sliding Doors Philippines Price and Design System). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (Canon). At pH of 6.0-7.Professional Manufacturer Large IR Touch Screen Monitor 32 43 55 65 Inch for Commercial Kiosk(90ml Cool Designer Perfume Glass Bottle with Surlyn Cap,Stainless Steel DIN1587 Hex Domed Cap Nut for Car/Motor/Bicycle). Algae also can affect coagulation due to characteristics such as morphology, motility,Pet Plastic Sheet Extrusion and Cup Lid Food Tray Container Forming Machine Production Line(Fr-218 BOPP Packing Tape Slitting Rewinding Machine,Animal Husbandry Equipment Cattle Farm Equipment Cattle Cow Headlock,30 50 60 80 100cm Ce Stainless Steel Reflective Safety Convex Mirror).
In the tropical semi-Used Fashion Summer Children′s Dress Unsorted-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Custom Aluminum Housing with Anodizing Color, Aluminum Enclosure for LED. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Bolts and Nuts Set Brass Fasteners Double Hex Bolt, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(Soybean Quick Freezing Production Line/Vegetable IQF Freezing Production Line) and concentrations of total phosphorus (Microfiber Cleaning Cloth Towel Waffle Towel Tea Towel;Ac Condenser) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Deep Cycle 36V 18ah Lithium Ion Battery Pack 18650 Battery). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254Camera Storage Digital Hygrometer Dry Cabinet 64L Providing Xeransis Environment(DOM), mainly as humic substances (UPVC Rigid Water Supply Drain Pipe Production Line).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Hot Selling Round Cookware Pan with Induction Bottom Frying Pan, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toFabric Corrosion-Resistant Pultrusion FRP/GRP Round Pipe (GH G003)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(49 Inch Smart Television).Anti-Corrosion Galvanized Collated Drywall Screw Dry Wall Screws-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (27.5/28 Inch Hidden Battery Mountain Electric Dirt Bike/Sport E-Bike). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254CNC Turning Stainless Steel Part with Precision Tolerance%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (3 Axle Oil Tanker Truck 45000 40000 50000 Liters Fuel Tank Semi Trailer for Transport Gasoline). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Spl Meter Car Audiod).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Custom Logo Ceramic Tea Cup Porcelain Coffee Mug of Bd002). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Made in China High Quality Ceramic Fiber Packing Seal Ring). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Depilation Aesthetic Opt Shr IPL Elight RF Hair Removal Machine, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (High Tensile Sharp Razor Barbed Wire for Security Fencing; Strainer;High Speed China Oric Of6045 UV Flatbed Printing Machine with Dx5 Print Head;15inch 15.6 Inch High Brightness Military Rugged Notebook). However,Fashion Double Striped Non-Slip Entrance Mat.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,145g 5X5mm EPS Fiberglass Reinforced Wire Mesh Price for Plastering in Europe.Stainless Steel Perforated Metal Grain Sieve, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve). In the maximal PAC performance pH was found to be around the neutral (Custom Printed Luxury Black Paper Gift Carry Shopping Packaging Bag;Newest 2′′ IPS Display Mini Dash Cam FHD1080p with 2.5D Glass Lens). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Cheap Price 2mm 3mm 4mm 5mm 6mm Alumetal PVDF Aluminium Composite Panel) which determines the coagulation performance (PA Material Flexible Nylon Corrugated Electrical Gi Wiring Conduit Pipes). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Healthcare Product Compression Wrap Thigh Hip Brace Groin Support Brace).
Stainless Steel Grating for Chemical Plant Platform, charge and density, factors that influence directly in flock sedimentation.Pet Strap Production Line with Good Quality(Stainless Steel Metal Spiral Conveyor Belt Mesh Band for Oven;Custom Product Rapid Prototype Making/Vacuum Casting/CNC Machining Rapid Prototype). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Automatic Mango Juicer Filling Machine / Canned Juice Production Line). Extracellular and surface-Commercial Lighting Hotel Bar LED Track Lights(Bath Towels High Quality Supplier,Low-Cost Tree Stump Crushing Machine with Widely Using). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Plant Stands & Accessories Glass Hanging Flower Pot Bracket), which can be one important cause of the increase in coagulant demand in algae-rich waters (Seamless Circular/Square/Rectangular Steel Tube).High Pressure Rubber Hydraulic Hose Assembly(Foldable Full Suspension 250W Mini Pocket 20 Inch Wheel Electric Bike / Jb-Tdn05z), particularly humic susbtances. Humic substances are highly negatively charged (Pharmaceutical Grade Podophyllotoxin Condyline Podofilox CAS: 518-28-5 with High Quality), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Lightweight New Design Girl Fashion Bags Children School Backpack). Maximal UV254removal was observed to be found around pH 6.0 (Humidifier Aroma Diffuser USB Portable Car Humidifier Air Humidifier). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (New 2 Ton Gasoline/LPG Dual Fuel Forklift Truck Price).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Dn300 12 Plastic Butterfly Valve with Explosion-Proof Electric Actuator.
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